There has been increasing concern recently about SARS-Cov-2 variants that might escape vaccines to some extent, as well as having different transmission rates (as the Kent variant does), and causing different severity of illness with higher mortality. I have added a vaccination efficacy modifier, var_eff, by variant, as a multiplier to the standard vaccination efficacy, vac_eff, to help model such potential variants that have a partial or total capability to escape vaccines, and this post shows examples of how that works, using a third variant introduced to the model on January 1st 2021. In addition, I have completed adding fSS (the fraction of people becoming seriously sick from each variant) and fmort (fatality of the variant) by Covid variant.
In my latest post on March 26th I described a new Coronavirus group model, based on work I had done as a UK case study in support of Prof. Alex de Visscher’s paper, in conjunction with Dr. Tom Sutton, on “Second-wave Dynamics of COVID-19: Impact of Behavioral Changes, Immunity Loss, New Strains, and Vaccination” which has now been published for peer review as a pre-print on Springer’s site at https://www.researchsquare.com/article/rs-195879/v1. I have now added the latest UK vaccination progress figures, and the UK Government’s announced intentions for the near future regarding Non Pharmaceutical Interventions (NPIs). I have also updated mortality and infection characteristics for the four different population groups in the model.
In my most recent post on February 12th, I described modelling work I had done in support of Prof. Alex de Visscher’s paper, in conjunction with Dr. Tom Sutton, on “Second-wave Dynamics of COVID-19: Impact of Behavioral Changes, Immunity Loss, New Strains, and Vaccination” which has now been published for peer review as a pre-print on Springer’s site at https://www.researchsquare.com/article/rs-195879/v1. I have now added vaccination and multiple variants I had already added to our previous model into the new grouped population model, and this blog post reports on progress with that new model.
This paper reports some parametric Coronavirus model runs I have made that compare, in particular, how the UK vaccine programme allows some NPI relaxation compared with a case with no vaccination. The outcome is that the vaccine programme in the UK has the potential to reduce the imposition of NPIs on March 7th by about 15%, without costing lives, this being the next time we in the UK are due for a major NPI review, potentially involving the return of schools at around March 7th.
Since my most recent posts on December 23rd and January 5th I have adjusted my model algorithms to model more than two variants, so that once better data is available on new variant characteristics, I can respond more quickly. The scenarios I have modelled show that presented with the threat of new variants, early proactive, preventative and decisive action in necessary as soon as a variant is identified. If a new variant is allowed to multiply and grow before appropriate Non Pharmaceutical Interventions are introduced (just as in the first days of the UK pandemic in March 2020, and with our UK March 23rd response) control of the virus is quickly lost.